Compressor crankshaft arrangement



Dec. 8,1970 4 s. A. PARKER 3,545,891A

COMPRESSOR CRANKSHAFT ARRANGEMENT Filed NOV. 1, 1968 lli-5.1

TTO/Q/VE YS United States Patent O 3,545,891 COMPRESSOR CRANKSHAFTARRANGEMENT Sidney A. Parker, Fort Worth, Tex., assignor to LennoxIndustries Inc., a corporation of Iowa Filed Nov. 1, 1968, Ser. No.772,496 Int. Cl. F04b 39/02; B23b 15/00 U.S. Cl. 417--372 9 ClaimsABSTRACT F THE DISCLOSURE BACKGROUND OF THE INVENTION This inventionrelates to an improved crankshaft arrangement for a compressor.

The crankshaft is one of the more expensive components of a refrigerantcompressor, along with the electric-drive motor and the basic castingfor compressor block. Prior crankshafts were commonly forged for highstrength requirements and cast for lesser strength requirements. Afterinitial forming, the crankshaft is rough ground. Pump passages are thendrilled in the crankshaft. The exterior surface of the crankshaft isthen coated and a portion of the coating is cut away to expose surfacesto be plated with copper which will prevent heat treatment of suchsurfaces. The crankshaft is heat treated and straightened. Portions ofthe exterior surface are then finish ground to the close tolerancesrequired.

Special xturing is required to grind the crankshaft since the centerlineof the eccentric portion of the crankshaft differs from the centerlineof the main shaft portion. It is apparent from the foregoing that themanufacture of conventional .cast or forged crankshafts is relativelycomplex, time-consuming and, therefore, expensive.

An object of the present invention is to provide an improved compressorcrankshaft arrangement, wherein the cost of fabrication is materiallyreduced.

A further object of the present invention is to provide an improvedcrankshaft arrangement for a compressor, including separate relativelyinexpensive centerless ground components prehardened, and then joined toone another by electron beam welding without adversely affecting theprior heat treating.

Yet another object of the present invention is to provide an improvedmethod for fabricating an inexpensive crankshaft for a compressor. Otherobjects and advantages of the present invention will become moreapparent hereinafter.

BRIEF DESCRIPTION OF THE DRAWING There is illustrated in the attacheddrawing a presently preferred form of the present invention, wherein:

FIG. 1 is a cross-sectional view of a compressor embodying an improvedcrankshaft of the present invention;

FIG. 2 is an enlarged fragmentary cross-sectional vieW of the compressorof FIG. 1;

FIG. 3 is a plan view of the flywheel of the crankshaft of FIGS. 1 and2; and

FIG. 4 is a detail sectional view taken generally along the line 4-4 ofFIG. l and illustrating a method of securing the compression mechanismwithin the outer housing of the compressor.

3,545,891 Patented Dec. 8, 1970 DESCRIPTION OF THE PREFERRED EMBODI-MENT OF THE INVENTION Referring to FIGS. 1 and 2, there is illustrated acompressor which embodies the crankshaft arrangement of the presentinvention. The compressor comprises a gastight outer housing whichincludes an upper shell 12 and a lower shell 14 integrally joined to oneanother, as, for example, by welding. To the bottom of the exteriorsurface of the lower shell 14 are Welded a plurality of suitablesupports or legs (not shown) by means of which legs the compressor maybe supported in upright position within a condensing unit or anair-conditioning unit.

Resiliently supported within the outer housing or casing of thecompressor 10 by means which will be more fully described hereafter is acompression mechanism 16 which includes a compressor block 18. Formed inthe compressor block is a cylinder 20 having a cylinder liner 22disposed therein for slidingly receiving a piston 24. The end of thecylinder liner 22 is closed by a discharge and suction valve assembly 26retained in place within the compressor block 18 by means of a cylinderhead 28. The cylinder head is held in place in the compressor block bysuitable means, including a Belleville spring 29 and a retaining ring30.

Journaled within the compressor block 18 is the crankshaft arrangement32 of the present invention. The crankshaft 32 is driven by electricdrive motor 36. The motor includes rotor 34 secured to the upper end ofthe crankshaft arrangement 32 for rotating same and stator 35 which isinductively connected to the rotor 34. 'Ihe stator 35 is xedly securedwithin the compressor block 18.

The means for actuating piston 24 include pistonconnecting rod 38 whichis aflixed to the lower end of the crankshaft arrangement 32. Uponrotation of the crankshaft 32, the connecting rod 38 will be moved toreciprocate piston 24 Within the cylinder liner 22.

Suction gas enters the compressor from a suction line and passes intothe space between the compressor block 18 and the outer housing 12. Thesuction gas ilows through the opening 44 in the end cap 46 over themotor 36 for cooling same and through the opening 47 in the compressorblock to the discharge and suction valve assembly 26. During the suctionstroke, suction gas is drawn through the suction valve in the dischargeand suction valve assembly 26 into the chamber defined between the liner22, piston 24 and assembly 26. On the discharge or compression stroke,the piston 24 forces the compressed gases through the discharge valve inthe discharge and suction valve assembly 26 and through the opening incylinder head 28 into the discharge line 48 and through the muffler 49in the discharge line to the discharge conduit 50 extending from the topof the compressor. The discharge conduit 50, which is adapted to beconnected in a refrigeration system, forms an extension of the dischargeline.

Turning now to a further more detailed consideration of the compressorcrankshaft or drive shaft arrangement 32, it is seen that the crankshaftis fabricated from a plurality of components suitably joined to oneanother to provide a unique arrangement. The crankshaft arrangement 32includes a hollow shaft portion 52 which is adapted to be journaled bybearings 54 and 56 within the compressor block 18. The shaft portion 52can be made from cold extruded high carbon steel, cut to length, heattreated and then centerless ground to close tolerances. A separate massor ywheel 58 is secured to the bottom of the shaft 52 by electron beamwelding. Such ywheel can be made from powdered metal or may be forged,for example. An opening 92 is provided in mass 58 for reducing theweight thereof, as desired.

The crankshaft arrangement 32 further includes a tubular centerlessground part 60 affixed within an opening 67 in the mass 58 by electronbeam welding. The part 60 can also be made from steel, for example, highcarbon steel, with the exterior surface thereof being heat treated toharden same. The axis of the tubular part 60 is parallel to the axis ofthe hollow shaft 52. Depending from the bottom of the tubular part 60 isa tube y62 which is adapted to be connected to the tubular part 60through the fitting 61. Tube 62 and fitting 61 are joined as asubassembly and are connected to part 60 so as to retain an end ofconnecting rod 38 journaled on part 60. The free end 62a of the tube 62is adapted to extend downwardly into a lubricant sump 64 defined in thelower end of the compressor casing or shell 14 and is adapted to lie inthe axis of the hollow shaft 32, so as to ingest lubricant from the sumpduring operation of the compressor. The tubular part 60 is provided withgenerally transverse or radially disposed openings 66 adjacent the upperend thereof which are in communication with a transverse or radialopening 68 in the mass 58. The opening 68 in the mass 58 is adapted tocommunicate with an annular groove or recess `69 defined in thecompressor block 18 which groove 69, in turn, communicates with passagemeans 70 formed in the compressor block. The passage means 70 maycomprise separate interconnected passages drilled in the compressorblock, with the ends of the passages then being plugged to provide acontinuous passage means communicating the crankshaft passage withannular space 72 between the hollow shaft 52, the compressor block 18and bearings 54 and 56. lt will be seen that in normal operation,lubricant ingested by the tube 62 from the sump 64 will pass through thetube 62, fitting 61, tubular part 60 and through the opening 68 andpassage means 70 into the annular space 72 for pressurized lubricationof the crankshaft bearing surfaces.

A vent opening 74 is provided in the top of the tubular part 60 suchthat at start-up of the compressor, any refrigerant in the tubular part60 will be vented through the vent opening 74 into the space between thecompressor block 18 and the outer housing. Thus, at start-up of thecompressor, lubricant will ow to the bearing surfaces, so as not tostarve the bearing surfaces. If refrigerant were carried to the bearingsurfaces at start-up, rather than lubricant, it would be possible todamage the bearing surfaces. Also, some lubricant or oil will be emittedfrom the groove 69 opening 74 during normal operation and will helplubricate the Wrist pin 37 which joins the connecting rod 38 to piston24.

The drive shaft 32 is readily fabricated as follows. Hollow shaft 52 maybe made from cold extruded steel cut to length, heat-treated and thencenterless ground to close tolerance. Part 60 is suitably formed andheattreated. The ywheel portion or mass 58 is forged or can be made frompowdered metal. Shaft 52 is inserted into opening 59 in flywheel 58 andelectron beam welded into place. Since the heat from such welding isextremely localized the heat-treated exterior surface portions of theshaft 52 are not adversely affected. Tubular part 60 which comprises theeccentrically disposed member for driving connecting rod 38 ispositioned in opening 67 in liywheel 50 and electron beam welded inplace so as not to adversely affect the heat-treated exterior of part60. Part 60 is secured in opening 67 with opening 66 in the part 60aligned with passage 68 in the flywheel or mass 58. Opening 67 extendsthrough the mass 58 such that vent opening 74 in the top of part 60 canproperly function. The connecting rod 38 is journaled on lthe part 60and fitting 61 is secured to the part 60 so as to retain the connectingrod 38 on part 60.

By this construction the diicult fixturing for grinding of the eccentricportion of a conventional crankshaft is avoided. The surface finishes ofa crankshaft made by the present method are consistently better thanthat of a conventionally formed crankshaft. The components of the newcrankshaft are easily formed and are relatively inexpensive. The overallcost of the crankshaft is materially reduced. It is also noted that theelectron beam welded joint is strong and that no splined connection isneeded to transmit the high torque from the electric-drive motor 36 andshaft 52 to mass 58 and eccentric post part 60 to which the connectingrod 38 is operatively secured.

Referring to FIG. 4, there is better illustrated the arrangement forresiliently supporting the compressor block 18 within the outer housing.The resilient supporting means includes a bracket 82 suitably secured tothe compressor block 18 by means of a bolt `83, a bracket 84 and aresilient block 86 secured between the brackets 82 and 84. Astirrup-like member 88 which is atiixed to the lower shell 14 of thehousing receives the bracket 84 and guides same for up and downmovement. The member 90, which is suitably secured to the upper shell 12provides a stop for limiting upper movement of the resilient supportingmeans. Thus, it will be seen that the bracket 82 is secured to thecompressor block, such that the compression mechanism 16 is atiixedthereto. The bracket 84 is movably received within the stirrup 88 whichlimits downward movement thereof. Upward movement of the resilient means80 is restricted by the stop 90.

There has been provided by the present invention an improved low-costcrankshaft arrangement for cornpressors. The crankshaft is fabricatedfrom inexpensive components that are readily assembled. The partscomprising the crankshaft are joined by electron beam welding so as notto adversely affect the heat-treated exterior surfaces of the hollowshaft or eccentric post part. The components can be separatelycenterless ground prior to assembly, obviating the need for complexixturing for grinding the eccentric part of the crankshaft such as isneeded in making a conventional crankshaft.

While I have shown and described a presently preferred form of myinvention, it will be understood that the invention is not limitedthereto, since it may be otherwise embodied within the scope of theattached claims.

I claim:

1. In a compressor, a crankshaft comprising a shaft having separate massmeans secured at one end thereof, conduit means secured to said massmeans including a tube extending from the mass means, with the free endof the tube disposed in the axis of the shaft and passage means in themass means adapted to communicate with the tube, there being a vent holein the mass means communicating with the passage means, and the shaftcomprisin g a hollow tubular member.

2. A compressor as in claim 1, wherein the mass means includes aiiywheel portion, a tubular part secured to the flywheel portion andextending downwardly from the flywheel portion and a fitting aliixed tothe tubular part for securing the tube to the flywheel portion.

3. A compressor as in claim 2, wherein the hollow tubular member and thetubular part are made from high carbon steel.

4. A compressor as in claim 2 wherein the exterior surface of the hollowtubular member is heat-treated and is connected to the flywheel portionby electron beam welding so as not to destroy the heat treat of theexterior surface.

5. A compressor as in claim 1, including a casing having a lubricantsump defined therein, compressor block means for receiving thecrankshaft in said casing, bearing means for journaling the crankshaftand passageway in the compressor block means communicating with thepassage means inthe mass means, the tube being disposed in the lubricantsump, whereby in operation, lubricant is ingested through the tube andpassed through the passage means in the mass means and the passageway inthe compressor block means to the bearing means for lubricating thebearing surfaces.

6. A method of fabricating a multiple component crankshaft for acompressor comprising aixing a separate mass means having passage meanstherein to the end of a shaft by electron beam welding, securing conduitmeans, including a tube, to the mass means with the free end of the tubedisposed in the axis of the shaft and with the tube communicating withthe passage means.

7. A method of fabricating a crankshaft for a compressor as in claim 6including forming a vent hole in the mass means communicating with thepassage means.

8. A method of fabricating a crankshaft for a compressor as in claim 6wherein the shaft is hollow including the steps of securing a tubularpart in an opening extending through the mass means, with the axis ofthe tubular part being parallel with the axis of the hollow shaft andaffxing a fitting to the tube and connecting same to the tubular part,the tubular part including opening means aligned with the passage meansin the mass means and a vent passage at the top thereof.

9. In a compressor, hollow tubular crankshaft means having aheat-treated exterior surface and a fly wheel portion connected to thecrankshaft by electron beam welding so as not to destroy the heat treatof the exterior surface, a tube secured to the crankshaft means andextending downwardly therefrom, with the free end of the tube having anopening disposed in the longitudinal axis of the crankshaft means, andvent means in the crankshaft means for venting material within thecrankshaft means to exterior of the crankshaft means at startup of thecompressor.

References Cited UNITED STATES PATENTS 2,766,929 10/ 1956 Rusch et al.230-206 3,049,285 8/ 1962 Doeg 230-206 3,075,686 1/1963 Steinhagen230-58 ROBERT M. WALKER, Primary Examiner U.S. Cl. X.R. 29-156.4

